I know this subject has been discussed in the past on the list and I've read through all discussions but I haven't been able to find a solution to the memory problems listed below... so here again...

It seems that the cassandra cluster I'm using is either leaking memory or just using more mem than I expected it to use.

Each host in the ring uses about 12G of ram while in some cases its entire dataset is only 1.5G (take for example .252.124 below with 1.54G)

I use extensive row caching so I expect memory consumption to be >= 1.5G but I don't understand why it gets up to 12G. Most of the times I don't care so much since I have plenty of memory however at times this gets me into GC storms and very slow responses. Also, I'd like to be able to load more data to the cluster and I'm hitting the memory wall, which I didn't expect.

In the cassandra.in.sh you'd notice that I do provide Xmx=12G but given that there's so little data I wouldn't expect the process to be using all of that. As a matter of fact I wanted to insert more data to the cluster but I stopped since it wasn't handling the load very well.

I suppose that at the end of the day I only need to know which knobs configure but after having played with the configuration for a long time I'm a little lost.